1. Field of the invention
The present invention relates to a method and apparatus for removing solvent from solvent vapor-laden air. More specifically, the present invention relates to a method and apparatus utilizing scrubbing and condensing techniques for removing liquid hydrocarbons such as a solvent from vapor-laden air such as perchlorethylene from air exiting from a conventional dry-cleaning machine.
2. Description of the Prior Art
Heretofore, many methods and apparatus have been proposed for treating a fluid such as a gas to remove hydrocarbon vapors such as oil vapor or solvent vapor therefrom. Examples of such previously proposed methods and apparatus employing scrubbing of a gas and condensing of a hydrocarbon liquid vapor therein such as a solvent, are disclosed in the following U.S. Patents:
______________________________________ U. S. Pat. No. Patentee ______________________________________ 741,855 Vollmann 877,520 Schmaltz 2,220,219 Crawford 3,800,505 Tarves, Jr. 3,927,153 Tarhan 4,044,078 Curtis, et al. 4,098,854 Knirsch, et al. 4,121,541 Kneissl, et al. ______________________________________
Also, it has heretofore been proposed to pass solvent vapor-laden air from a dry-cleaning machine through an apparatus or device for removing solvent from the air. Examples of such heretofore proposed devices and machines for removing solvent from solvent vapor-laden air exiting from a dry-cleaning machine are disclosed in the following U.S. Patents:
______________________________________ U. S. Pat. No. Patentee ______________________________________ 3,807,948 Moore 4,083,704 Knopf ______________________________________
As will be explained in greater deal in connection with the description of the method and apparatus of the present invention, the method and apparatus of the present invention differ from the previously proposed methods and apparatus by providing for the spraying of a coolant over a condensing medium having coolant therein while passing solvent vapor-laden air upwardly through the condensing medium to condense the solvent vapor into the condensing liquid coolant.
Also, to improve the efficiency of the method and apparatus of the present invention, such method and apparatus can provide for enhanced heat transfer of heat from the solvent vapor-laden air prior to passing the solvent vapor-laden air through the condensing medium. This is accomplished by first passing the heated solvent vapor-laden air upwardly through a cooling chamber wherein water is sprayed into the chamber; and by means of an extended surface non-wetting packing, the heat transfer to droplets of water in the cooling chamber from the solvent vapor-laden air is enhanced.
The liquid mixture of coolant and solvent is fed to a separator/reservoir where the solvent is separated from the coolant, the coolant is recooled for reuse and the solvent is drained off for reuse.